Process for obtaining citrus fiber from citrus pulp

ABSTRACT

A process is disclosed for obtaining citrus fiber from citrus pulp. Citrus fiber is obtained having a c* close packing concentration value of less than 3.8. The citrus fiber can be obtained having a viscosity of at least 1000 mPa.s, wherein said citrus fiber is dispersed in standardized water at a mixing speed of from 800 rpm to 1000 rpm, to a 3 w/w% citrus fiber/standardized water solution, and wherein said viscosity is measured at a shear rate of 5 s-1 at 20° C. Citrus fiber can be obtained having a CIELAB L* value of at least 90. The citrus fiber can be used in food products, feed products, beverages, personal care products, pharmaceutical products or detergent products.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application, Ser. No.13/812,603, filed Jan. 28, 2013, and entitled PROCESS FOR OBTAININGCITRUS FIBER FROM CITRUS PULP, which claims the benefit of PCT PatentApplication, Serial No. PCT/US11/045975, filed Jul. 29, 2011, entitledPROCESS FOR OBTAINING CITRUS FIBER FROM CITRUS PULP, which claims thebenefit of Provisional Patent Application Serial No. 61/369,204 filedJul. 30, 2010, entitled PROCESS FOR OBTAINING CITRUS FIBER FROM CITRUSPULP, which applications are hereby incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The present invention is directed to a process for obtaining citrusfiber from citrus pulp. The resulting dried citrus fiber is useful as afood additive in food products, feed products and beverages. The citrusfiber is also useful in personal care, pharmaceutical or detergentproducts.

BACKGROUND OF THE INVENTION

The prior art describes methods for extracting citrus fiber from citruspulp.

For example, U.S. Pat. No 7,094,317 (Fiberstar, Inc.) describes aprocess for refining cellulosic material from organic fiber plant mass(such as citrus fruit). The process discloses a first step of soakingthe organic fiber plant mass in an aqueous solution, draining theorganic fiber plant mass and allowing it to sit for sufficiently longtime to enable cells in the organic fiber plant mass to open cells andexpand the organic fiber plant mass. The soaking step requires at least4 hours and is reported to be critical to get the materials to fullysoften. The soaked raw material is then refined under high shear anddried.

W.O. Patent Application No 94/27451 (The Procter & Gamble Company)describes a process for producing a citrus pulp fiber, wherein first anaqueous slurry of citrus pulp is prepared which is then heated to atemperature of 70° C. to 180° C. for at least 2 minutes. The slurry isthen subjected to a high shear treatment.

W.O. Patent Application No 2006/033697 (Cargill, Inc.) describes aprocess of extracting citrus fiber from citrus vesicles. The processincludes washing citrus vesicles with water, contacting the water washedvesicles with an organic solvent to obtain organic solvent washedvesicles, desolventizing the organic solvent washed vesicles andrecovering dried citrus fiber therefrom.

While the prior art reports that citrus fiber with useful properties isobtained, there remains a need to further improve the characteristics ofcitrus fiber.

Hence, it is an object of the present invention to develop a process forobtaining citrus fiber from citrus pulp having improved propertiesversus the citrus fiber of the prior art. It is further an object of thepresent invention to obtain a citrus fiber which has good hydrationability and viscosifying properties.

SUMMARY OF THE INVENTION

The present invention, according to one aspect, is directed to a processfor obtaining citrus fiber from citrus pulp. In one embodiment, citruspulp is treated to obtain homogenized citrus pulp. The process furthercomprises a step of washing the homogenized citrus pulp with an organicsolvent to obtain organic solvent washed citrus pulp. The organicsolvent washed citrus pulp is desolventized and dried, and citrus fiberis recovered.

In another aspect the present invention is directed to a citrus fiberhaving a c* close packing concentration value of less than 3.8.

In a preferred embodiment, the citrus fiber has a viscosity of at least1000 mPa·s, wherein said citrus fiber is dispersed in standardized waterat a mixing speed of from 800 rpm to 1000 rpm, preferably 900 rpm, to a3 w/w % citrus fiber/standardized water solution, and wherein saidviscosity is measured at a shear rate of 5 s⁻¹ at 20° C. In anotherpreferred embodiment, the citrus fiber has a CIELAB L* value of at least90.

In yet another aspect, the present invention is directed to a blend ofcitrus fiber of the present invention and plant-derived (e.g. derivedfrom cereals) fiber, citrus fiber obtained from citrus peel or citrusrag (segment membranes, core) and combinations thereof.

In yet another aspect, the present invention is directed to a foodproduct, a feed product, a beverage, a personal care product,pharmaceutical product or a detergent product comprising the citrusfiber according to the present invention.

In yet another aspect, the present invention is directed to the use ofthe citrus fiber as a texturiser or viscosifier in food products, feedproducts, beverages, personal care product, pharmaceutical product ordetergent product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a process in accordance with apreferred embodiment of the present invention.

FIGS. 2 a and 2 b are an illustration in accordance with a test methodused in the present application.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention is directed to a process forobtaining citrus fiber from citrus pulp.

The term “citrus pulp,” as used herein, refers to the pectinaceous andcellulosic material contained in the inner, juice-containing portion ofcitrus fruit. It is a co-product of the orange juice industry, resultingfrom the mechanical extraction of the juice. Citrus pulp is sometimesalso referred to as coarse pulp, floaters, citrus cells, floating pulp,juice sacs, citrus vesicles or pulp. Citrus pulp typically has a watercontent of at least about 80 wt % and usually from about 90 to about 98wt %.

The term “citrus fiber,” as used herein, refers to a fibrouspecto-cellulosic component obtained from citrus pulp.

The process according to the present invention may be used for obtainingcitrus fiber from citrus pulp from a wide variety of citrus fruit,non-limiting examples of which include oranges, tangerines, limes,lemons, and grapefruit. In one preferred embodiment, citrus fiber isobtained from orange pulp.

In the process according to the present invention, citrus pulp istreated to obtain homogenized citrus pulp. Optionally, the citrus pulpmay be washed with water prior to homogenization. Sometimes, citrus pulpmay be provided in a frozen or dried state which requires thawing orrehydration prior to homogenization. Preferably, the citrus pulp isadjusted with water to a dry matter content of 5 wt % or less. While notintending to be bound to any theory, it is believed that thehomogenization treatment causes disruption and disintegration of wholepulp cells and cell fragments. Homogenization can be effected by anumber of possible methods including, but not limited thereto, highshear treatment, pressure homogenization, colloidal milling, intensiveblending, extrusion, ultrasonic treatment, and combinations thereof.Preferably, the power input (power per unit volume) for effectinghomogenization is at least 1000 kW per cm³ of citrus pulp.

In a preferred embodiment of the present invention, the homogenizationtreatment is a pressure homogenization treatment. Pressure homogenizerstypically comprise a reciprocating plunger or piston-type pump togetherwith a homogenizing valve assembly affixed to the discharge end of thehomogenizer. Suitable high pressure homogenizers include high pressurehomogenizers manufactured by GEA Niro Soavi, of Parma (Italy), such asthe NS Series, or the homogenizers of the Gaulin and Rannie seriesmanufactured by APV Corporation of Everett, Mass. (US).

During the pressure homogenization, the citrus pulp is subjected to highshear rates as the result of cavitation and turbulence effects. Theseeffects are created by the citrus pulp entering the homogenizing valveassembly from the pump section of the homogenizer at a high pressure(and low velocity). Suitable pressures for the process of the presentinvention are from 50 bar to 1000 bar.

Depending on the particular pressure selected for the pressurehomogenization, and the flow rate of the citrus pulp through thehomogenizer, the citrus pulp may be homogenized by one pass through thehomogenizer. However, more than one pass of the citrus pulp may berequired.

In one embodiment, the citrus pulp is homogenized by a single passthrough the homogenizer. In a single pass homogenization, the pressureused is preferably from 300 bar to 1000 bar, more preferably from 400bar to 800 bar, even more preferably from 500 bar to 750 bar.

In another preferred embodiment, the citrus pulp is homogenized bymultiple passes through the homogenizer, preferably at least 2 passes,more preferably at least 3 passes through the homogenizer. In amultipass homogenization, the pressure used is typically lower comparedto a single-pass homogenization and preferably from 100 bar to 600 bar,more preferably from 200 bar to 500 bar, even more preferably from 300bar to 400 bar.

Optionally, the citrus pulp may be subjected to a heat treatment priorto homogenization. Preferably, the temperature used in the heattreatment can vary from 50° C. to 140° C. for a period of from 1 secondto 3 minutes. The heat treatment may be used for pasteurization of thecitrus pulp. For pasteurization, the heat treatment preferably employs atemperature of from 65° C. to 140° C., preferably from 80° C. to 100° C.for a period of from 2 seconds to 60 seconds, preferably from 20 secondsto 45 seconds. Pasteurization is preferred to inactivate pectinesterasesfor preventing cloud loss and to inactivate spoilage micro-organisms forenhancing storage stability.

The homogenized citrus pulp is then contacted with an organic solvent.In one aspect, the organic solvent extracts water, flavors, odors,colors and the like from the citrus pulp. The solvent should preferablybe polar and water-miscible to better facilitate removal of the desiredcomponents. Available solvents may include lower alcohols such asmethanol, ethanol, propanol, isopropanol, or butanol. Preferred solventsare ethanol, isopropanol, and combinations thereof. The solvent may beprovided in aqueous solution. The concentration of solvent in thesolvent solution most often ranges from about 70 wt % to about 100 wt %.In one embodiment, a 75 wt % aqueous ethanol solution is used assolvent. In a preferred embodiment, a 90 wt % aqueous ethanol solutionis used as solvent. In general, solvents will remove water-solublecomponents at lower concentrations and oil-soluble components at higherconcentrations. Optionally, a more non-polar co-solvent may be added tothe aqueous alcohol to improve the recovery of oil-soluble components inthe citrus pulp. Examples of such non-polar solvents include ethylacetate, methyl ethyl ketone, acetone, hexane, methyl isobutyl ketoneand toluene. The more non-polar solvents may be added at up to 20% ofthe solvent mixture. Many solvents, such as ethanol, have a lower heatof vaporization than that of water, and therefore require less energy tovolatilize than would be needed to volatilize an equivalent mass ofwater. The solvent preferably is removed and reclaimed for reuse.

Preferably, the citrus pulp is contacted with organic solvent at asolids-to-solvent weight ratio of at least about 0.25:1, preferably atleast about 0.5:1, and often at least about 0.75:1, from about 1:1 toabout 5:1, or from about 1.5:1 to about 3:1, based on the wet weight ofthe solids. In one embodiment, the solids-to-solvent ratio is about 2:1.

Extraction can be accomplished using a single stage but preferably isperformed using multi-stage extraction, e.g., a two-, three-, orfour-staged extraction process, and preferably using countercurrentextraction. There is no particular upper limit contemplated on thenumber of extraction stages that may be used. FIG. 1 schematicallyillustrates a preferred embodiment in which a two-stage countercurrentextraction process employs first and second solvent extractors 25 a and25 b, respectively.

After homogenization 10, homogenized citrus pulp is fed into the secondextractor 25 b. An aqueous ethanol solvent is fed from a solvent tank 26into the first solvent extractor 25 a. Spent solvent from the firstsolvent extractor 25 a is fed into the second solvent extractor 25 b,while the extracted citrus pulp from the second solvent extractor 25 bare fed into the first solvent extractor 25 a. Spent solvent from thesecond solvent extractor 25 b may be fed into an evaporator 35(optional) to separate solids (e.g., sugars, acids, colors, flavors,citrus oils, etc.) from the spent solvent, which can be condensed andreturned to a still 24. Still bottoms (predominately water) areseparated and removed.

After each extraction stage, liquid is preferably further removed. Onesuitable device is a decanter centrifuge. Alternatively, a sieve, a beltfilter press or other device suitable for removing liquids, may be used.

Citrus pulp from the first solvent extractor 25 a is fed to adesolventizer 30. The desolventizer 30 removes solvent and water fromthe solids remaining after extraction, enabling the solvent to bereclaimed for future use and also ensuring that the product is safe formilling and commercial use. The desolventizer 30 can employ indirectheat to remove significant amounts of solvent from the solid residue.Alternatively, direct heat can be provided for drying, e.g., byproviding hot air from flash dryers or fluidized bed dryers. Directsteam may be employed, if desired, to remove any trace amounts ofsolvent remaining in the solids. Vapors from the desolventizer 30preferably are recovered and fed to the still 24 to reclaim at least aportion of the solvent.

Retention time in each extraction step may vary over a wide range butcan be about 5 minutes or less per extraction step. The temperature inthe solvent extractor(s) depends on such factors as the type of solventused but most often ranges from about 4° C. to about 85° C. atatmospheric pressure. Temperatures can be appropriately increased ordecreased for operation under super- or sub-atmospheric pressures.Optionally, techniques such as ultra-sound are used for enhancingefficiency of the extraction process. By maintaining a closed system,solvent losses during extraction, desolventizing, and distillation canbe minimized. Preferably, at least about 70 wt % of the solvent isrecovered and reused. A solvent make-up stream delivers fresh solventinto the solvent tank 26 to replenish any solvent that is not recovered.

In a preferred embodiment, the process according to the presentinvention further comprises a comminuting or pulverizing step prior todesolventizing and drying. Suitable methods include, but are not limitedto, grinding, milling, crushing, high speed mixing, or impingement.Comminution or pulverization can be beneficial to disintegrate anyclumps or aggregates that are left after the removal of liquid with thebelt filter pressing step. This step furthermore facilitates the removalof solvent. While not wishing to be bound by theory, it is believed thatcomminution or pulverization further opens the fibers. As a result ofthis, the solvent is more uniformly distributed and easier to be removedin the subsequent desolventization and drying step. In yet anotherpreferred embodiment, the comminuting or pulverizing step is used incombination with adding and dispersing water or a blend of water and anorganic solvent (as described hereinbefore) to enhance desolventizationand drying, and achieve the desired humidity in the finally obtainedcitrus fiber for a particular end use.

In another preferred embodiment, the process according to the presentinvention further comprises a comminuting or pulverizing step afterdrying. This post-drying comminuting or pulverizing step may be carriedout to further reduce the particle size of the citrus fiber, to improveflowability, dispersability, and/or hydration properties.

In yet another preferred embodiment, the process according to thepresent invention further comprises the step of subjecting the citruspulp to a processing aid. Preferably, the processing aid is selectedfrom the group consisting of enzymes, acids, bases, hydrocolloids,vegetable fiber, bleaching agent, and combinations thereof. Preferably,the processing aid is mixed with the citrus pulp prior tohomogenization.

In one aspect of the present invention, the processing aid may be usedto tailor the properties of the finally obtained citrus fiber.

Preferred enzymes include, but are not limited thereto, pectinase,protease, cellulase, hemicellulase and mixtures thereof. When enzymesare used, they are to be used prior to any heat treatment that wouldinactivate them, and preferably also prior to homogenization.Inactivation by heat treatment is however desired once the desiredeffect is achieved.

Preferred acids include, but are not limited thereto, citric acid,nitric acid, oxalic acid, ethylenediaminetetraacetic acid andcombinations thereof. Citric acid is however most preferred as it is afood grade acid.

A preferred base is caustic soda.

Preferred hydrocolloids include, but are not limited thereto, pectin,alginate, locust bean gum, xanthan gum, guar gum, carboxymethylcelluloseand combinations thereof.

A bleaching agent may further enhance the color properties (i.e. renderthe citrus fiber even more whiter). A preferred bleaching agent ishydrogen peroxide.

The citrus fiber obtained by the process according to the presentinvention has improved properties over other citrus fibers from theprior art. Especially, the citrus fiber has good swelling behavior,hydration ability and viscosifying properties. It is capable of buildingviscosity under relatively low shear.

The citrus fiber of the present invention has a c* close packingconcentration of less than 3.8 w %, anhydrous basis. Preferably, the c*close packing concentration is less than 3.6, even more preferably lessthan 3.4, and most preferably less than 3.2 w %, anhydrous basis. Thedetermination of the c* close packing concentration is described in thetest method section herein below.

The citrus fiber preferably has a moisture content of 5% to 15%, morepreferably from 6% to 14%. Preferably, at least 90% of the volume of theparticles have a diameter of less than 1000 micrometers, preferably from50 micrometers to 1000 micrometers, more preferably from 50 micrometersto 500 micrometers, even more preferably from 50 micrometers to 250micrometers.

The citrus fiber preferably has a viscosity of at least 1000 mPa·s,wherein said citrus fiber is dispersed in standardized water at a mixingspeed of from 800 rpm to 1000 rpm, preferably 900 rpm, to a 3 w/w %citrus fiber/standardized water solution, and wherein said viscosity ismeasured at a shear rate of 5 s⁻¹ at 20° C. Preferably, the viscosity ata shear rate of 5 s⁻¹ at 20° C. is at least 2000 mPa·s, more preferablyat least 3000 mPa·s, even more preferably at least 4000 mPa·s, even morepreferably at least 5000 mPa·s and up to 15000 mPa·s. The preparation ofthe standardized water, and the method for measuring viscosity isdescribed in the test method section herein below.

The citrus fiber according to the present invention further has goodemulsification properties, as shown in the examples. The D4,3 value inthe oil-rich phase is typically below 15 micrometers for the citrusfiber of the present invention.

In a preferred embodiment, the citrus fiber of the present inventionalso has excellent whiteness properties, even without the need for usingbleaching agents. The citrus fiber typically has a CIELAB L* value of atleast 85. But with the process according to the present invention, it ispossible to obtain much higher L* values. Thus, according to anotheraspect, the present invention is directed to a citrus fiber having aCIELAB L* of at least 90, preferably at least 92, even more preferablyat least 93. Preferably, the citrus fiber has a CIELAB b* value of lessthan 20, even more preferably of less than 15. The method fordetermining the CIELAB L* and b* values is described in the test methodsection herein below. As discussed hereinbefore, bleaching agents maystill be used as processing aids in the process to even further improvethe whiteness of the citrus fiber.

The citrus fiber according to the present invention can be blended withother fibers, such as plant-derived (e.g. from vegetables,grains/cereals) fibers, with other citrus fibers such as citrus fiberobtained from citrus peel or citrus rag, or combinations thereof. Theblend can be in dry or liquid form.

In another aspect, the citrus fiber of the present invention and theblends described hereinbefore may be used in food applications, feedapplications, beverages, personal care products, pharmaceutical productsor detergent products. The amount of citrus fiber (or blend) to be useddepends on the given application and the desired benefit to be obtained,and lies within the knowledge of a skilled person.

Food applications may include, but are not limited to, dairy products,frozen products, bakery products, fats and oils, fruit products,confectionary, meat products, soups, sauces and dressings. Dairyproducts include, but are not limited to yoghurt, fromage frais, quark,processed cheese, dairy desserts, mousses. Frozen products include, butare not limited to, ice cream, sorbet, water ice. Bakery productsinclude, but are not limited to, cakes, sweet goods, pastry, patisserie,extruded snacks, fried snacks. Fats and oils include, but are notlimited to, margarines, low fat spreads, cooking fats. Fruit productsinclude, but are not limited to, fruit preparations, yoghurt fruitpreparations, conserves, jams, jellies. Confectionary includes, but isnot limited to, candy, chocolate spreads, nut-based spreads. Meatproducts include, but are not limited to, chilled or frozen processedmeat and poultry, preserved meat products, fresh sausage, cured sausageand salami.

Beverages may include concentrates, gels, energy drinks, carbonatedbeverages, non-carbonated beverages, syrups. The beverage can be anymedical syrup or any drinkable solution including iced tea, and fruitjuices, vegetable based juices, lemonades, cordials, nut based drinks,cocoa based drinks, dairy products such as milk, whey, yogurts,buttermilk and drinks based on them. Beverage concentrate refers to aconcentrate that is in liquid form.

Personal care products may include cosmetic formulations, hair careproducts such as shampoos, conditioners, creams, styling gels, personalwashing compositions, sun-creams and the like.

Detergent products may include hard surface cleaning products, fabriccleaning or conditioning products, and the like.

Test Methods

1. Preparation of Standardised Water

Dissolve 10.0 g NaCl (e.g. Merck 1.06404.1000, CAS [7647-14-5]) and 1.55g CaCl₂.2H₂O (e.g. Merck 1.02382.1000, CAS [10035-04-8]) in lowconductivity water (e.g. milli-Q

Ultrapure Millipore 18.2 MΩcm), and make up to 1 liter to preparestandardized water stock. Take a 100ml aliquot of the standardized waterstock and make up to 1 liter with low conductivity water.

2. Measuring c* Close Packing Concentration

2.1 Principle

Citrus fiber samples (n≥10) are wetted with ethylene glycol, dispersedin standardised tap water, and subjected to the MCR301 controlled shearstress (CSS) oscillatory test. The citrus fiber dispersions are measuredby 0.25w/w% increments in the range of 1.75-5.00 w/w %. The linearviscoelastic range (LVR) complex moduli G* is plotted againstconcentration. The close-packing concentration c* is determined via thetwo tangents crossover method on a linear scale.

2.2 Apparatus

-   -   Anton Paar MCR301 rheometer with coaxial cylinder configuration        (TEZ150P-CF Peltier at 20° C.) with vane probe ST24-2D/2V/2V-3D,        grooved measuring cup CC27/T200/SS/P and circulating cooling        water bath set at 15° C. The equipment must be clean and dry,        and the MCR301 units must be turned on 30 minutes before use.        Checks should be made according to the instruction manual of the        supplier (see instruction manual). The Circulator bath and pump        should be at all times in use to avoid burning of the peltier        unit. According to the manufacturer, the water bath must be        filled with demineralised water containing maximum 30% of        antifreeze (e.g. ethylene glycol).    -   RWD 20 Digital IKA stirrer and lower the paddle (4 bladed        propeller 07 410 00)    -   600 ml Duran glass beaker (ø10 cm)    -   Laboratory balance having a precision of 0.01 g    -   Hard plastic soup spoon

2.3 Procedure

System Start-Up

Start up the circulator bath (filled with demineralised water+30%ethylene glycol (e.g. Merck 1.00949.1000, CAS [107-21-1])) andafterwards the rheometer according to the procedure explained in theinstruction manual. Select the workbook and perform the initialisationprocedure according to the instruction manual.

System Calibration

The standard calibration check procedure for the MCR301 is fullydescribed in the instruction manual and should be performed according tothe instruction manual. The MCR301 instruments must be ready (initiatedand all parameters checked) before testing the citrus fiber dispersions.The ST24 measuring system CSR should be set to 1 and the CSS value(Pa/mNm) should be fixed with certified calibration Newtonian oil (e.g.Cannon N100, available from Cannon Instrument Company, State College,Pa. 16803, USA).

Sample Preparation

-   -   Place a 600 ml glass beaker on the laboratory balance, and zero        the balance.    -   Weigh into the beaker the required grams (x) of citrus fiber, to        the nearest 0.01 g, according to the moisture content (m) of the        citrus fiber sample: x=3c/[(100−m)/100], for any given        concentration c in w/w % (samples starting at 1.75 w/w %, to        5.00 w/w % with 0.25w/w % increments). The moisture content m        should be determined by infra-red moisture balance (Sartorius MA        30), as weight loss at 105° C. with automatic timing, typically        3-4g citrus fiber covering the entire bottom of the aluminium        pan. The moisture content (m) of citrus fiber is in weight        percent (w %).    -   Weigh into a second 600 mL beaker the required grams (w) of        standardised tap water, to the nearest 0.1 g, according to the        moisture of the citrus fiber sample: w=270.0−x    -   Place the beaker with CPF on the laboratory balance, zero the        balance, add 30.0g (to the nearest 0.1 g) of ethylene glycol,        put the beaker out of the balance and mix the content with the        plastic spoon thereby wetting the whole powder (this operation        is performed within 60 seconds).    -   Pour at once the standardised tap water on to the wet citrus        fiber and mix the content with the plastic spoon by repeated        clockwise and anti-clockwise rotations (this operation is        performed within 60 seconds).    -   Position the glass beaker with its content (citrus fiber,        ethylene glycol, standardised tap water) underneath a RWD 20        Digital IKA stirrer and lower the paddle (4 bladed propeller 07        410 00) into the paste until 2 cm from the bottom of the glass        beaker.    -   Adjust the paddle speed (rpm) to 900 rpm and stir 10 minutes at        900 rpm.    -   Cover the beaker with aluminium foil and allow 24 hours rest        prior measurement    -   Pour the required amount of CPF dispersion into the cylindrical        cup of the rheometer and insert immediately the vane probe ST24        (starch cell probe) into the cylinder containing the CPF        dispersion

Sample Analysis

-   -   Perform CSS oscillatory test with the MCR301 according to the        manual instructions, with 2 segments:    -   segment 1: non recording, 10 minutes at 20° C. (equilibration)    -   segment 2: recording, 1971 seconds at 20° C., 50 measuring        points integration time 100 to 10 seconds log, torque 1 to        10,000 μNm log, frequency 1 Hz

Results

At low stress, where the G* (versus stress) is showing constant plateauvalues, average the G* results over the linear viscoelastic range. Usingthe software “LVE Range”, the end of the linear viscoelastic region inthe CSS experiments can be determined.

Plot the LVR G* versus concentration. The first tangent at lowconcentration (below c*) has a much lower slope than the second tangentat high concentration (above c*). Using linear fitting (e.g. withMicrosoft® Excel®), the crossover point of both tangents occurs at theclose packing concentration c*.

3. Measuring Viscosity

Add citrus fiber to standardized water in a beaker with a paddle mixerto obtain a 3 wt % citrus fiber dispersion with a total volume of 300ml. Prior to adding the citrus fiber, create a vortex by adjusting thepaddle speed to 900 rpm using an IKA Overhead Mechanical Stirrer RW20equipped with a 4-bladed propeller stirrer. Then add the citrus fiberquickly (before the viscosity builds up) on the walls of the vortexunder stirring (900 rpm using an IKA Overhead Mechanical Stirrer RW20equipped with a 4-bladed propeller stirrer). Continue stirring for 15minutes at 900 rpm. Store the sample for 12 hours at 20° C.

Then perform the viscosity test with a rheometer (e.g. Anton PaarMCR300), in accordance with the rheometer's instructions, in function ofshear rate (from 0.01 to 100 s⁻¹) at 20° C.

The viscosity (mPa·s) is determined at a shear rate of 5 s⁻¹.

4. Emulsification

Prepare an emulsion containing 20 wt % sunflower oil, 2 wt % citrus pulpfiber and the remaining standardized tap water. First disperse the fiberin the water phase under high-shear mixing (8000 rpm) for 1 minute. Thenadd the oil to the water phase under high-shear mixing (13500rpm) for 5min at room temperature and constant mixing speed.

Particle size distribution of the obtained emulsions is measured usinglaser light scattering (e.g. using a Malvern MasterSizer X). Typically,a bimodal particle size distribution is observed (see FIG. 2 a ). Thepeak on the right corresponds with the particle size distribution of theoil-rich fraction of the emulsion (oil droplets+soluble fibers), whilethe peak on the left corresponds with the particle size distribution ofthe insolubles-rich fraction of the emulsion (e.g. cellulose).

The Malvern software allows the determination of an overall volume meandiameter D(4,3), but cannot provide the D(4,3) of the separatefractions. However, as fractions show a log-normal distribution, a peakdeconvolution can be applied.

Peak deconvolution can be performed as follows: transfer the raw datafrom the Malvern

MasterSizer X into Microsoft Excel™ for further analysis. It is assumedthat the overall volume mean diameter (as obtained by the MalvernMicroSizer) equals the sum of 2 log-normal distributions.

The equation for a log-normal distribution can be found in literature.The lognormal distribution is a two-parameter distribution withparameters μ′ and σ_(T). The probability density function for thisdistribution is given by:

${f\left( T^{\prime} \right)} = {\frac{1}{\sigma_{T^{\prime}}\sqrt{2\pi}}e^{{- \frac{1}{2}}{(\frac{T^{\prime} - \mu^{\prime}}{\sigma_{T^{\prime}}})}^{2}}}$

where T′=In(T), where the T values correspond with the particle sizes inthe present method, and

-   -   μ′=mean of the distribution    -   σ_(T)=standard deviation of the distribution

Deconvolution can be performed based on this equation and the resultsobtained are shown in FIG. 2 b.

A good fit is found between the raw data distribution and the appliedmodel. The mean (μ′) of the peaks of each distribution corresponds withthe D(4,3) of each phase (oil-rich phase and insolubles-rich phase).This assumption can be made due to the fact that the particles follow analmost perfect log-normal distribution.

5. Measuring Colour (CIELAB L*, b* Values)

CIE L*a*b* (CIELAB) is the most complete color space specified by theInternational Commission on Illumination (Commission Internationaled'Eclairage). It describes all the colors visible to the human eye andwas created to serve as a device independent model to be used as areference. The L* and b* values of the citrus fiber are obtained byplacing citrus fiber (in powder form) in the glass cell (fill the cellto about a half) of the colorimeter and analyse the sample in accordancewith the user's instructions of the colorimeter. The colorimeter used isa Minolta CR400 Colorimeter.

EXAMPLES 1. Examples 1-5

Orange pulp is adjusted with water to a dry matter content of 5 wt % toobtain 720 kg of the orange pulp. The pulp is charged to a pressurehomogenizer (Niro Soavi, type NS3006L) and recirculated (maximum 5 bar)while adjusting the feed pressure to 700 bar.

The precipitation tank is filled with a centrifuge pump with 1.8 m³ of75-80 wt % ethanol solution from the first washing tank. The homogenizedpulp is sent straight to the precipitation tank with a volumetric pump.Agitate while filling the tank, and continue stirring for about 30minutes.

Adjust the speed of the centrifuge decanter (Flottweg centrifuge,900R150, decanter Z23-3) to 5260 rpm. The differential speed is adjustedto 30 rpm and the diameter adjustment to 145 mm. Charge the product tothe centrifuge decanter with a volumetric pump, and recover the product.

First ethanol washing: a tank is filled with 1.5 m³ of 82 wt % ethanolsolution from the second ethanol washing. Feed the recovered productinto the tank, and agitate for about 30 minutes. The washed product isthen sent to a 100 μm rotative filter with a volumetric pump, andproduct is recovered.

Second ethanol washing: send the recovered product from the firstethanol washing to a tank filled with 1.4 m³ of 85 wt % ethanolsolution, and agitate for about 30 minutes. The washed product is thensent to a 100 μm rotative filter with a volumetric pump, and product isrecovered.

The recovered product from the second ethanol washing is then fed to ascrew press. The speed and pressure is adjusted to obtain a dry mattercontent of about 30 wt %.

The product is then milled using a Lodigue, 900M340, type FM300DIZ, andmill for 15 to 30 minutes.

The product is then fed to a vacuum dryer (ECI) and mixed for about 90minutes. Add slowly 40% (based on dry matter content of the product) ofa 60% ethanol solution. Dry with 95° C. water for 4 hours under vacuum.

Recover the orange pulp fiber.

5 samples (Ex. 1-5) are prepared, originating from Brazilian orange pulpfrom different sources.

2. Comparative Example

The orange pulp fiber obtained by the process of the present inventionis compared to commercially available citrus fibers:

Citri-Fi 100 and Citri-Fi 100 M 40, orange fiber derived from orangepulp (Fiberstar Inc.)

Herbacel AQ-Plus Citrus Fibre F/100, and Herbacel AQ-Plus Citrus FibreN, lemon fibers derived from lemon peel (Herbstreith & Fox Inc).

3. Results

3.1 c* Close Packing Concentration

c* (w %, anhydrous basis) Example 4 2.80 Example 5 3.09 Citri-Fi 1004.04 Herbacel AQ-Plus Citrus Fibre N 3.94

The c* close packing concentration of the citrus fiber according to thepresent invention is significantly lower than those of the commerciallyavailable fibers.

3.2 Viscosity

viscosity (mPas) Example 1 7085 Example 2 4455 Example 3 13000 Example 46900 Example 5 22890 Citri-Fi 100 508 Herbacel AQ-Plus Citrus FibreF/100 250

A significant difference in viscosity is observed between the orangefibers according to the present invention (ex. 1-5), and thecommercially available fibers.

Furthermore, an additional test has been carried out. It has beenassessed at with mixing speed (versus the 900 rpm used in the testmethod), about the same level of viscosity increase could be obtainedfor a commercial citrus fiber. For the Citri-Fi 100 sample, a viscosityof 7545 mPa·s could be obtained if the citrus fiber is dispersed in thestandardized water only at high shear rates (9500 rpm). This shows thebenefit of the citrus fiber of the present invention in that it canbuild viscosity even when dispersed in solution at low shear rates. Thismeans that the citrus fiber of the present invention is much easier toprocess and provides economical advantages (equipment and energy) overthe fibers of the prior art.

3.3 Emulsification

D4, 3 (μm) D4, 3 (μm) insolubles- oil-rich phase rich phase Example 17.7 74.0 Example 5 9.2 77.5 Citri-Fi 100 M 40 31.1 59.8 Herbacel AQ-PlusCitrus Fibre F/100 18.1 113.9

It can be observed that the D4,3 value in the oil-rich phase is muchlower for the orange fiber of the present invention (example 1, 5). Thismeans that the oil droplets in this phase are much smaller and henceprove the better emulsification behavior of the orange fiber of thepresent invention.

3.4 Colour

L* b* Example 1 93 12 Citri-Fi 100 M 40 87 15.3 Herbacel AQ-Plus CitrusFibre F/100 88 11.7

The orange fiber of the present invention has an L* value above 90, andis whiter than the commercial fibers.

What is claimed is:
 1. A process for preparing citrus fibers from citruspulp, the process comprising: treating citrus pulp to obtain homogenizedcitrus pulp, wherein the treating comprises pressure homogenization;subjecting the homogenized pulp to a bleaching agent; washing thehomogenized citrus pulp with an organic solvent to obtain organicsolvent washed citrus pulp; feeding the organic solvent washed citruspulp through a screw press at a speed and pressure to obtain a drymatter content of about 30 wt % or more; milling the screw pressedcitrus pulp for at least 15 minutes; vacuum drying the milled citruspulp for at least 90 minutes adding at least 40% (db) of a 60% solventsolution; vacuum drying the vacuum dried citrus pulp with water at atemperature of at least 95° C. for at least 4 hours to remove thesolvent; and recovering citrus fibers from the citrus pulp, wherein thecitrus fiber has a D4,3 value less than 15 micrometers, wherein therecovered citrus fibers have a moisture content in a range of from 5% to15% and a c* close packing concentration of less than 3.8 w %, anhydrousbasis.
 2. The process according to claim 1, wherein the treatingcomprises pressure homogenization using a pressure of from 50 bar to1000 bar.
 3. The process according to claim 2, wherein said treatingcomprises a single-pass pressure homogenization using a pressure of from300 bar to 1000 bar.
 4. The process according to claim 2, wherein saidtreating comprises a multi-pass pressure homogenization comprising atleast 2 passes, using a pressure of from 100 bar to 600 bar.
 5. Theprocess according to claim 1, wherein the citrus pulp is subjected to aheat treatment prior to the homogenization treatment at a temperature offrom 50° C. to 140° C. for a period of 1 second to 3 minutes.
 6. Theprocess according to claim 1, wherein said process further comprisessubjecting said citrus pulp to a processing aid selected from the groupconsisting of enzymes, acids, bases, hydrocolloids, vegetable fiber, andcombinations thereof.
 7. The process according to claim 1, wherein thebleaching agent comprises hydrogen peroxide.
 8. The process according toclaim 1, wherein the organic solvent is selected from the groupconsisting of methanol, ethanol, propanol, isopropanol, butanol, andcombinations thereof.
 9. The process according to claim 1, wherein theorganic solvent comprises ethanol, isopropanol, or combinations thereof.10. The process according to claim 9, wherein the organic solventfurther comprises an organic non-polar co-solvent.
 11. The processaccording to claim 10, wherein the non-polar co-solvent comprises up to20 wt % of a mixture of a polar organic solvent and the non-polarorganic solvent.
 12. The process according to claim 10, wherein theorganic non-polar co-solvent comprises ethyl acetate, methyl ethylketone, acetone, hexane, methyl isobutyl ketone, toluene, or a mixturethereof.
 13. The process according to claim 2, wherein said treating isa multi-pass pressure homogenization comprising at least 3 passes, usinga pressure of from 100 bar to 600 bar.
 14. The process according toclaim 1, wherein the organic solvent has a solids-to-solvent weightratio of at least about 0.5:1.
 15. The process according to claim 1,wherein the organic solvent has a solids-to-solvent weight ratio in arange of from about 1:1 to about 5:1.
 16. The process according to claim1, wherein the organic solvent has a solids-to-solvent weight ratio in arange of from about 1.5:1 to about 3:1.
 17. The process according toclaim 1 further comprising applying a processing aid to the citrus pulp.18. The process according to claim 17, wherein the processing aidcomprises an enzyme, an acid, a base, a hydrocolloid, a vegetable fiber,or a mixture thereof.
 19. The process according to claim 17, wherein theprocessing aid is applied to the citrus pulp prior to homogenization ofthe citrus pulp.
 20. The process according to claim 1, wherein therecovered citrus fiber has a diameter of less than 1000 micrometers.